12 
ADVANTAGES OF DRAINING AND SUBSOIL PLOWING. NO. 1. 
ADVANTAGES OF DRAINING AND SUBSOIL FLOW- 
ING.— No. 1. 
Soils that are composed of stiff clay, light 
sand or gravel, are not often benefitted by sub- 
soil plowing, unless previously prepared for 
this operation. Stiff clays ought in all cases, 
to be first thoroughly underdrained by some one 
of the most approved methods now in use. The 
water, which is held in these soils, and which 
escapes only by slow evaporation keeps the 
land cold, and in a condition totally unfitted to 
the growth of any useful vegetable. Even rice, 
which is particularly an aquatic plant, requires 
a change of water to secure its growth. Stag- 
nant water would be fatal to this crop. How 
much more certainly deleterious, is a soil thus 
saturated, for all those useful vegetable products, 
which require a well-divided, well-drained po- 
rous soil, through which the roots can range in 
every- direction in search of food. Such soils 
are especially termed cold, and for this reason. 
It is a well-established principle, that sensible 
heat becomes latent or concealed, when it is 
absorbed by water or any other substance, which 
in consequence of this absorption, is changed 
from a solid to a liquid, or from a liquid to a 
gaseous state. Thus, if we take a piece of ice 
at zero, and expose it to a temperature above the 
freezing point, its own temperature will be slowly 
raised till it reaches 32°, at which it changes 
to a liquid. At this point it will remain, no mat- 
ter how great the heat to which it may be ex- 
posed, till all has melted. From the instant the 
ice reached 32°, the heat absorbed till it is con- 
verted into water, becomes latent; and this is 
not perceptible to sensation, or by the use of 
any philosophical instrument hitherto construct- 
ed. It would be a vast stride in science, should 
such an instrument at any time hereafter be 
discovered. 
If the water be then exposed to a heat above 
212°, it will, as in the case with ice, be gradu- 
ally carried up to that point, when, if not shut 
in by a powerful vessel, as in steam boilers, so 
as effectually to prevent evaporation, it will re- 
main at 212°, though exposed to the same tem- 
perature as before, till all the water is converted 
into vapor. And, just in the same manner as 
ice absorbed a large quantity of sensible heat 
and rendered it latent, to change it from a solid 
to a liquid, so does the liquid absorb a large 
amount of heat to convert it into vapor, which, 
by this conversion, and solely in consequence 
of it, is rendered latent or insensible. 
Now, if a farmer once understands this prin- 
ciple, he will readily comprehend why soils that 
are saturated with water, are with peculiar pro- 
priety termed cold and unproductive. The 
heat of the sun and atmosphere, which is ab- 
sorbed by porous soils, and thus elevates their 
temperature and stimulates vegetation, is almost 
exclusively exhausted in evaporating the super- 
fluous water of wet soils. Instead of the bene- 
ficial effect of warming the ground, which it 
was intended to have produced, the heat is 
employed to remove the water which the lazy 
or shiftless owner should have got rid of by un- 
derdraining ; and the roots of the plants are 
pinched or entirely repulsed by their cold, clam- 
my bed, instead of being kindly invited to a 
wide and rapid extension in a genial soil. 
Draining has this further and great advantage, 
that by leading off' the water from the soil at its 
base, the cracks, pores or interstices, just before 
occupied by the water, are at once filled by the 
air which presses after it (for there can be no 
vacuum) ; and this air imparts whatever sensi- 
ble heat it may possess above that cf the soil, 
till an equilibrium of temperature is restored. 
Another beautiful result follows the transmis- 
sion of air through the soil, when the tempera- 
ture of the former is more elevated than the 
latter. The atmosphere always holds watery 
vapor, which we have seen absorbs a large 
quantity of latent heat. When the temperature 
of the air is lowered, it is compelled to part 
with a portion of this vapor, which* is converted 
into sensible moisture, dew or rain, and which 
is thus deposited in the soil, and directly in con- 
tact with the roots ; and while engaged in this 
operation another beneficent law compels it to 
give up all the latent heat required by its change 
from water to vapor, and which on being made 
sensible, is at once absorbed by the soil. 
The air which presses after the water drawn 
off by underdrains, also carries with it large 
quantities of fertilizing gases, as ammonia, car- 
bonic acid, &c. These, although existing in mi- 
nute proportions through the atmosphere, yet 
afford to growing vegetation a large aggregate of 
their ultimate product. The air contains from 
over 94 to 99 per cent, of the elements which 
make up the entire vegetable growth, whether 
it be wood, grain, grass, roots or other products ; 
and although much of this amount may be and 
undoubtedly is derived from the soil, yet its mi- 
nute division and the circulation of air through 
it, contribute greatly to the augmentation of the 
crop. Besides the nutritive gases brought into 
the soil by a free circulation of air, others are 
formed in fertile soils, from the same cause. 
The oxvgen brought into contact with the vege- 
table matter in the soil, converts it into carbonic 
acid, and being formed at the mouth of the root- 
lets of the plants, is immediately carried into 
their circulation and deposited, thus contributing 
to their growth. Ammonia may be formed by the 
attractive and condensing properties of the 
alumina and carbon of the soil, and nitric acid, 
such an efficient aid in vegetation, is undoubt- 
edly thus produced by fertile calcareous soils, 
or such as contain large proportions of lime. 
The benefits resulting from the circulation of 
air through a fertile, w T ell-drained soil can 
scarcely be overrated. It was the secret of Jethro 
Tull's great success, in his system of thorough 
pulverization. By this* means, he secured the 
ready admission and escape of the air, which 
not only brought with it heat, moisture and all 
the organic elements of the crops, but by acting 
on the mineral constituents of the soil, it set 
such of them free as were necessary to furnish 
their inorganic portions, and thus the whole pro- 
duct was made up with scarcely the addition of 
manures. An originally fertile soil, with its 
mineral ingredients properly proportioned, when 
